Method of selective shutting off of water flow in oil wells



Patented I Oct. 1, 1935 METHOD OF SELECTIVE SHUTTING OFF OF WATER FLOW IN OIL WELLS Irving E. Muskat, Pittsburgh, Pa., as'signonto Gulf Research & Development Corporation, Wilmington, Del., a corporation of Delaware No Drawing. Application January 9, 1935, Serial No. 1,068

3 Claims. (Cl. 166-21) UNITED STATES PATENT OFFICE This invention relates to methods of selective close the pores. Hydrolysis is rather quick and shutting off of water flow in oil wells; and it comprises a method of closing pores and voids containing water in formations through which 5 an oil well passes without materially interfering with the flow of oil, wherein sulfur monochloride (S2012) is forced into the well under pressure in such a way as to displace the water in the formation ahead of it, with a pause after the introduction of the sulfur monochlorideduring which pressure is not released and the monochloride is allowed to hydrolyze in place with depos'tion of sulfur, this sulfur clogging and plugging the pores; the sulfur monochloride so introduced being often diluted with more or less petroleum oil to retard hydrolysis and the monochloride frequently containing sulfur in solution to augment the sulfur yielded by hydrolysis; all as more fully hereinafter set forth and as claimed.

A deep oil well passes through a variety of formations some of which are usually wet and contain water or brine. Inflow of water or brine from these formations is undesirable. On the other hand, inflow of oil from an oil-containing formation is desirable. Sometimes the oil-bearing formations and the water-bearing formations are in rather close proximity. In the art, no very good way of selectively shutting off the water flow without interfering with the oil flow is known. Where the oil flow is minor in amount, all inflow may be shut off by various expedients, all well known in the art, and including forming a concrete sheath in situ on the oil well walls. i

I have found that I can accomplish a selective shutting off of water and brine by the expedient of injecting sulfur monochloride into the well under rather heavy pressure, so that it enters and passes outwa d through the pores of the wet formations, d splacing the brine or water ahead of it. On discontinuing introduction of the monochloride, while maintaining the pressure, during a pause, the sulfur monochloride in the formations hydrolyzes, depositing free sulfur effectively clogging the pores.

Sulfur monochloride is a heavy oily liquid, S2012, soluble in petroleum oils but hydrolyzing quickly on contact with water. Hydrolysis results in the delivery of most of the contained sulfur in the form of free sulfur, with production of HCl and minor amounts of thionic acids. The exact course of the reaction depends on circumstances but in all cases there is a deposition of free sulfur in a form well adapted to I have found that in practical embodiments of the present invention, I can secure better results by diluting the monochloride with a petroleum oil, such as crude oil, naphtha, etc. This dilu- 5 tion results in a delayed action; the diluted monochloride can travel further in the wet pores, expelling water ahead of it prior to the time that diffusion from remaining water produces a pore-plugg ng amount of sulfur. 10

In a practical embodiment of the present invention, 2 parts by weight of commercial liquid sulfur monochloride were dissolved in parts of dry crude oil. The mixture was introduced into a'well under heavy pressure, a pressure 15 greater than the normal well pressure. With a slow feed of the diluted monochloride into the well and a tolerably high pressure, the monochloride passed outward from the well faces for a considerable distance. Slow hydrolysis took 20 place. In the formation, the voids and pores are more or less localized and there are what may be regarded as major channels formed by communicating voids with a column of the liquid monochloride in each channel. On this column, 25 retained moisture in the minor pores and voids in the formation acts by diffusion to produce solid sulfur by hydrolysis; the action being the quicker the less the amount of diluting oil pres-- ent, In this particular instance, in order to 30 secure the necessary penetration and the necessaryplugging, it was found expedient to use the stated proportion of sulfur monochloride to oil; a 2 percent solution. Sometimes less and sometimes more diluent oil is desirable; this 35 depending upon the speed of action which is desired.

In this particular case, no free sulfur was dissolved in the oil-sulfur monochloride mixture. But in many cases I dissolve free sulfur in the 40 sulfur monochloride up to, say, 25 per cent its weight. This provides additional sulfur plugging the pores.

In the use of the present invention, the well is out of commission but a short time. After the 45 monochloride is introduced and has been given time to hydrolyze, the excess monochloride is pumped out and normal operation of the oil well resumed.

What .I claim is:

1. In the selective plugging of water-bearing formations in oil wells, the process whichcomprises introducing into the well under a pressure greater than the normal well pressure liquid sulfur monochloride in amount sufficient to enter the pores and pass outward from the well a. considerable distance, continuing the pressure while discontinuing introduction to give a pause for hydrolysis, then removing excess sulfur mon- 5 ochloride and resuming the delivery of oil from the well.

2. In the process of claim 1, diluting the sul- Iur monochloride with a petroleum oil to secure a delayed action.

3. In the process of claim 1, dissolving tree sulfur in the sulfur monochloride, thereby augmenting the amount of sulfur produced in hydrolysis.

IRVING E. MUSKAT. 

